This invention relates to a swing check valve mounted in a valve chamber for pivotal movement between open and closed positions.
Heretofore, a clapper-type swing check valve member which swings freely from a closed position has been supported by an arm with a loose fit between the arm and the clapper valve member so that the valve member may freely seat on the face of the adjacent seat in a closed position. In addition, a restraining strap or loop on the rear face of the valve member in which the arm fits has permitted movement of the arm. Turbulence in the flow of fluid through the check valve causes the clapper valve member to oscillate or vibrate to the limit of the clearances provided in the pin connection of the arm to the valve member and in the strap to cause impacting of the arm against the strap and also against the pin which results in a fatigue failure in some instances unless overly designed parts are provided for the strap and the pin connection. Repeated impacts of the arm against the restraining strap tends to effect a failure of the strap unless an unusually heavy cross-section of the strap is provided and also unless an unusually strong connection is provided between the strap and the back face of the check valve member on which the strap is secured.
Prior art arrangements have not been successful in providing an effective arrangement to minimize the fatigue exerted by the check valve member continually seeking its seated position and repeatedly floating back and forth from seated to unseated position resulting in a continual movement of the arm against the strap and the pin connection of the arm.